Before a teacher plans a unit, he or she should identify the big ideas that students will understand at the end of the unit. Fortunately, there are national and state level standards designed to help teachers focus in the most important ideas in each discipline. This is an example of "unpacking" these standards to prepare to teach a particular physics topic, linear motion. It has four main sections, including (1) an assembly of the standards related to the topic (national and state); (2) a description of what the standards mean as far as what students should know; (3) a list of what students need to know before they start the unit; and (4) a list of possible preconceptions students may bring to the unit. - fogleman
Learning Goals for Physics: Linear Motion
An Excerpt From The NSES Standard for MOTIONS AND FORCES
Objects change their motion only when a net force is applied. Laws of motion are used to calculate precisely the effects of forces on the motion of objects. The magnitude of the change in motion can be calculated using the relationship F = ma, which is independent of the nature of the force. Whenever one object exerts force on another, a force equal in magnitude and opposite in direction is exerted on the first object. - NSES at http://www.nap.edu/readingroom/books/nses/6e.html
This page will focus on the part of this standard focusing on motion:
Objects change their motion only when a net force is applied. Laws of motion are used to calculate precisely the effects of forces on the motion of objects.
What do these statements mean about what students need to know about linear motion?
In order to distinguish between the different ways that an object may be moving, students neet to be able to describe and analyze the motion of an object. Right now, I am only interested in what students need to know to analyze linear motion. Two dimensional motion, including projectile motion and uniform circular motion will be addressed in following units. Periodic motion will also be addressed later.
Students should to be able to:
Measure and report values of position and time. This includes measuring small distances using a meter-stick as well as larger distances. Students should be able to determine the precision with which they should report these measurements. Students should be able to measure time with a stopwatch.
Operationally define velocity as how an object's position changes in one second. Because velocity indicates both the speed and direction of linear motion, students should be able to relate it an object's change in position along a number line. Because motion is often described with a variety of terms, students should be able to explain the terms distance, displacement, location, and distance traveled in terms of position. Likewise, students should also be able to explain how speed and rate are related to velocity for an object traveling at a constant velocity.
Use a calibrated speed to empirically determine an unknown distance.
Plot position time for an object at rest or traveling at constant velocity to the right or left. Students should also be able to describe a particular trip given it position time graph.
Determine the slope of a position time graph, and argue that this slope is the object's velocity. Relate the formula for the slope of the position time graph to related equations in math: the y-intercept form of an equation of a line and D = RT.
Distinguish between constant and accelerated motion in terms of how it appears in "motion maps", position time graphs, and how they are sensed by observers.
Operationally define acceleration as how an object's velocity changes in one second, and identify the units of acceleration as "meters/sec per sec."
Plot position time for an object traveling with constant acceleration. Students should also be able to describe a particular trip given its velocity time graph.
Use a motion detector to distinguish a variety of different linear motions, including slowing down while traveling to the right and speeding up traveling to the left.
Use kinematic equations derived from the definition of average acceleration to solve a variety of linear motion problems.
What do students need to know to learn kinematics?
Students should already be able to
Identify and use both metric and English units of measurement for length using a ruler or measuring tape.
Convert between different units of measurement for both position and velocity.
Plot an Y vs X graph both by hand, calculator, and computer. Students should also be able to draw "best fit lines" through linear data as well as tangents at points on curvilinear data.
Students should be able to do basic algebra, including isolating a particular variable in a linear equation.
What preconceptions might students have?
Students might think
all motion in the same direction as indistinguishable, i.e. not consider the difference between constant velocity and constant acceleration.
the motion equation from algebra, D=RT, sufficient for analyzing all motion.
in order for an object to have a positive acceleration, its velocity must be positive.
the acceleration of a vertically launched object at the top of its path is zero.
if an object's acceleration is zero, its velocity must be zero, and/or vice versa.
From [[http://homepage.mac.com/vtalsma/syllabi/2943/handouts/misconcept.html#force Children's Ideas in Science]]:
1. Time can be measured without establishing the beginning of the interval.
2. The location of an object can be described by stating its distance from a given point, ignoring direction.
3. The distance an object travels and its displacement are always the same.
4. An object’s speed is the same as its velocity.
5. If an object is accelerating, then the object is speeding up.
6. An object’s acceleration cannot change direction.
7. Acceleration always occurs in the same direction as an object is moving.
8. If an object has a speed of zero (even instantaneously), it has no acceleration.
--Hapkiewicz, A. (1992). Finding a List of Science Misconceptions. MSTA Newsletter, 38(Winter’92), pp.11-14.
Learning Goals for Physics: Linear Motion
An Excerpt From The NSES Standard for MOTIONS AND FORCES
Objects change their motion only when a net force is applied. Laws of motion are used to calculate precisely the effects of forces on the motion of objects. The magnitude of the change in motion can be calculated using the relationship F = ma, which is independent of the nature of the force. Whenever one object exerts force on another, a force equal in magnitude and opposite in direction is exerted on the first object. - NSES at http://www.nap.edu/readingroom/books/nses/6e.html
This page will focus on the part of this standard focusing on motion:
Objects change their motion only when a net force is applied. Laws of motion are used to calculate precisely the effects of forces on the motion of objects.
What do these statements mean about what students need to know about linear motion?
In order to distinguish between the different ways that an object may be moving, students neet to be able to describe and analyze the motion of an object. Right now, I am only interested in what students need to know to analyze linear motion. Two dimensional motion, including projectile motion and uniform circular motion will be addressed in following units. Periodic motion will also be addressed later.
Students should to be able to:
What do students need to know to learn kinematics?
Students should already be able to
What preconceptions might students have?
Students might think
From [[http://homepage.mac.com/vtalsma/syllabi/2943/handouts/misconcept.html#force Children's Ideas in Science]]:
1. Time can be measured without establishing the beginning of the interval.
2. The location of an object can be described by stating its distance from a given point, ignoring direction.
3. The distance an object travels and its displacement are always the same.
4. An object’s speed is the same as its velocity.
5. If an object is accelerating, then the object is speeding up.
6. An object’s acceleration cannot change direction.
7. Acceleration always occurs in the same direction as an object is moving.
8. If an object has a speed of zero (even instantaneously), it has no acceleration.
--Hapkiewicz, A. (1992). Finding a List of Science Misconceptions. MSTA Newsletter, 38(Winter’92), pp.11-14.